CN115513471A - A kind of screen printing preparation method of self-supporting oxygen evolution anode - Google Patents

Abstract

The invention discloses a screen printing preparation method of a self-supporting oxygen evolution anode, which has the advantages that: (1) The preparation process of the screen printing is adopted, the process is simple, the quality control is easy to realize, the process repeatability is good, and the method is suitable for batch preparation of large-area OER electrodes; the prepared oxygen evolution anode has higher repeatability and uniformity and is far superior to commercial IrO ₂ 、RuO ₂ The performance of the electrode. (2) In the screen printing process, a three-dimensional NiFeM-LDH self-supporting structure is formed by in-situ growth, so that the stability and the conductivity of the electrode are enhanced, and the release of an oxygen product is facilitated; the polymer adhesive which is not beneficial to conductivity is not needed, so that the conductivity is further enhanced; no noble metal load. (3) The oxygen evolution catalytic performance is greatly improved through an etching process, a third component doping and a heat treatment process, and the obtained oxygen evolution anode has extremely high oxygen evolution activity, stability and repeatability.

Description

A kind of screen printing preparation method of self-supporting oxygen evolution anode

technical field

The invention belongs to the field of water electrolysis, and in particular relates to a screen printing preparation method of a self-supporting oxygen evolution anode.

Background technique

At present, due to the increasingly serious environmental problems caused by the overuse of fossil fuels, it has become an urgent need for the whole society to develop new environmentally friendly energy carriers as a substitute for traditional fossil fuels. Hydrogen has become one of the most promising alternative fuels in the future due to its advantages of high mass-to-energy density and clean and efficient energy conversion.

The relatively mature large-scale hydrogen production processes in the industry mainly include methane reforming and coal gasification hydrogen production technologies. However, due to the large energy loss, trace CO and high carbon dioxide emissions, the two are difficult to apply to the current hydrogen energy utilization. The main carrier - the application requirements of fuel cells. However, hydrogen production by alkaline water electrolysis has attracted wide attention as the main method of green hydrogen production in recent years due to its advantages of high technological maturity, simple process, and high purity of hydrogen produced.

In the reactor/electrolytic cell for hydrogen production by electrolysis of alkaline water, the electrode material is the place for electrochemical reaction and the core component of the reactor. Among them, the oxygen evolution reaction on the surface of the anode involves a 4-electron transfer process, and the slow kinetics of the electrode process limits the improvement of the hydrogen production efficiency by alkaline water electrolysis. Therefore, the design and development of high-performance, easily scalable non-precious metal oxygen evolution anode batch preparation process has always been a research hotspot in the field of water electrolysis.

Traditional noble metal electrode materials such as iridium, ruthenium, and platinum were first used as oxygen evolution electrode materials, and are widely used in anodes for pure water electrolysis and alkaline water electrolysis. However, in the industrial application of large-scale green hydrogen production, the high cost of materials has significantly increased the difficulty of its large-scale transformation. (Q.Gao et al.Structural design and electronic modulation of transition-metal-carbideelectrocatalysts toward efficient hydrogen evolution[J].Advanced Materials,2019,31(2).) Therefore, finding non-noble metal oxygen evolution materials to replace noble metals has great application value .

In the research and development of non-noble metal OER materials, transition metals such as iron, cobalt, nickel, and molybdenum exhibit high oxygen evolution activity due to their incompletely filled d orbitals. Among them, NiFe layered double hydroxide (NiFe-LDH) has become one of the most promising oxygen evolution materials. (J.Wang et al.Recent progress in cobalt-based heterogeneous catalysts for electrochemical water splitting[J].Advanced Materials,2016,28(2):215–230.) Corrigan et al. (DACorrigan.The Catalysis of the Oxygen EvolutionReaction by Iron Impurities in Thin Film Nickel Oxide Electrodes[J].J.Electrochem.Soc,1987,134:377-384.) reported for the first time the catalytic synergy between Fe and Ni-based electrocatalytic materials in the oxygen evolution reaction in alkaline media. Fe doped into NiO _x or Ni(OH) ₂ interface, under the condition of 25% iron doping, the overpotential is only 320mV, which is much lower than 380mV of the material without iron doping. MS Burke et al. (MS Burke et al.Cobalt–Iron(Oxy)hydroxide Oxygen Evolution Electrocatalysts: The Role of Structure and Composition on Activity,Stability,and Mechanism[J].J.Am.Chem.Soc,2015,137:3638-3648. ) suggested that Fe element would improve the interface OER performance of Ni(OH) ₂ film. The research results show that the initial overpotential of the Ni(OH) ₂ film decreased by about 50mV after being placed in Fe-rich KOH for one week; at the same time, the characteristic peak of the oxidation conversion from nickel hydroxide to oxyhydroxide moved from 0.43V to 0.51 V, which indicates the high activity of Fe-based active sites in the mixed cation phase due to the Ni(OH) catalyzed interfacial structure transformation from NiOOH to Ni _{1 -x} Fe _x (OOH) due to the doping of Fe in the electrolyte, It is the main reason for the enhanced OER performance of the catalytic interface.

Although LDH-based materials have the advantages of low cost, easy preparation, good durability, and low electrical conductivity, they generally need to be mixed with binders to prepare electrodes for practical applications. The introduction of non-conductive adhesives often brings two effects that are not conducive to OER: first, it increases the charge transfer resistance at the electrode/solution interface; second, the bubbles formed by OER will destroy the powdery LDH and the adhesive. The connection between them leads to the collapse of the catalytic layer. (J. Hou et al. Rational design of nanoarray architectures for electrocatalytic watersplitting [J]. Advanced Functional Materials, 2019, 29 (20).) For this reason, the preparation process does not require the presence of a binder, and the NiFe-LDH electrode with a self-supporting structure was developed and prepared. attention.

At present, the methods for preparing self-supporting NiFe-LDH electrodes generally include ion exchange method, hydrothermal method, and electrodeposition method. LuoYu et al. (L.Yu et al.Cu nanowires shelled with NiFe-layered double hydroxidenanosheets as bifunctional electro-catalysts for overall watersplitting[J].Energy&EnvironmentalScience,2017,10(8):1820–1827.) in self-made copper nanowires 2D NiFe-LDH nanowires were electrodeposited on top to prepare a self-supporting three-dimensional core-shell Cu@NiFe-LDH electrode. Its overpotential is as low as 199mV at 10mA·cm ^-2 and only 315mV at 1A·cm ^-2 . Qiu Yang et al. (Q.Yang et al.Hierarchical construction of an ultrathin layered double hydroxidenanoarray for highly-efficient oxygen evolution reaction[J].Nanoscale,2014,6(20):11789–11794.) prepared fractions by a two-step hydrothermal method The layered NiCoFe-LDH structure has an overpotential of 233mV at 30mA·cm ^-2 , which is significantly improved compared to 438mV of the non-self-supporting prepared material. Bin Liu et al. (Bin Liu, etal.Amorphous Multimetal Alloy Oxygen Evolving Catalysts[J].ACS Materials Letters,2020,2(6):624-632.) prepared NiFeMoB alloy by a room temperature synthesis method, at 500mA·cm ^-2 , the lowest OER overpotential is only 220mV. Zhang Xinghe et al. (ZL2020106255211) patented a preparation method of a NiFe-LDH three-dimensional self-supporting OER electrode containing high-valent iron. They prepared NiFe-LDH electrodes containing high-valent iron in situ on the nickel foam skeleton by hydrothermal reaction, and used them as oxygen evolution anodes in 1mol L ^-1 KOH electrolyte solution, when the current density was 10mA cm ^-2 , the oxygen evolution overpotential is 239mV, and when the current density is 500mA·cm ^-2 , the oxygen evolution overpotential is 350mV. Geng Dongsheng et al. (ZL2020112489048) announced a hydrothermal synthesis process for the preparation of NiFe-LDH. The preparation process is as follows: firstly, Cu is loaded on the nickel foam skeleton by a hydrothermal method, and then a self-supporting NiFe-LDH nano-array structure is grown on its surface in situ by a hydrothermal method. The OER overpotential of the oxygen evolution anode is 226mV at 10mA·cm ^-2 in 1mol·L ^-1 KOH electrolyte solution. However, in actual operation, this type of hydrothermal method is limited by the reaction equipment and cannot achieve large-scale preparation. Zheng Zongmin et al. (ZL201810337104X) disclosed a preparation method suitable for large-area self-supporting oxygen evolution electrodes. The specific preparation process is as follows: firstly, a layer of basic oxide is loaded on the conductive substrate, and then soaked in the transition metal mixed salt solution for reaction, aiming to vertically grow ultra-thin flake-shaped transition single metals and multi-metals on the conductive substrate Hydroxide, to obtain a self-supporting high-performance oxygen evolution electrode. The oxygen evolution anode is at 50mA·cm ^-2 , and the oxygen evolution overpotential is about 300mV.

In summary, although the self-supporting LDH material has excellent oxygen evolution activity, there are few patent reports on the preparation process that can ensure the repeatability and uniformity of the electrode for batch preparation. In the above-mentioned preparation process of self-supporting LDH materials, the ion exchange method needs to prepare a pure-phase hydroxide layer, and its growth conditions are not easy to control; in the hydrothermal synthesis process, in order to obtain a better lamellar structure, it is often necessary to add Surfactant, its material preparation is limited by the reaction equipment, and it is difficult to realize the batch preparation of large-area sheet electrodes; although the electrodeposition method can grow two-dimensional materials on conductive substrates, however, in the process of large-area electrode deposition, The complex current distribution of the electrochemical system makes it difficult to achieve uniform growth of two-dimensional materials.

Contents of the invention

In view of the problems existing in the above-mentioned OER preparation technology, the present invention aims to propose a screen printing preparation method suitable for self-supporting oxygen evolution NiFeM-LDH (M=Mo, Mn, Co, W, P, B, etc.) series anodes . The in-situ growth of NiFeM-LDH (M=Mo, Mn, Co, W, P, B, etc.) materials on porous nickel substrates is realized by adding a vacuum adsorption heating platform to the screen printing machine. Its characteristic advantages are: (1) In situ growth in the instantaneous process of screen printing to form a three-dimensional NiFeM-LDH self-supporting structure without noble metal loading. (2) The prepared NiFeM-LDH electrode has high OER activity and stability in alkaline medium. (3) The screen printing process is simple, easy to achieve quality control, and has good process repeatability. The prepared oxygen evolution anode has high repeatability and uniformity, and is suitable for batch preparation of large-area OER electrodes.

The present invention provides following technical scheme, and concrete steps are:

A method for preparing a self-supporting oxygen evolution anode by screen printing, the steps are as follows:

(1) Substrate pretreatment: Porous nickel-based materials were used as electrode substrates, cleaned in acetone, absolute ethanol and deionized water, etched in water-soluble acid, and finally dried at room temperature before use.

(2) Preparation of metal salt solution and reducing agent solution: dissolving nickel salt and iron salt in deionized water to prepare metal salt solution or dissolving nickel salt, iron salt and third component M salt in deionized water to prepare metal salt solution ; dissolving the water-soluble reducing agent in deionized water to prepare a reducing agent solution; the third component M is one of Mo, Mn, Co, W, P, B or a mixture of two or more.

(3) Install a temperature-controllable vacuum adsorption heating platform on the printing plane of the screen brushing machine; place the porous nickel-based material on the heating platform and fix it, use a screen with a mesh number of 50-400, and use screen printing technology on the porous nickel-based material. Paint a layer of metal salt solution prepared in step (2) on the bottom of the material; then, use the reducing agent solution prepared in step (2) as the screen printing slurry, and repeat the alternate screen printing metal salt solution and reducing agent solution; The self-supporting oxygen evolution anode of NiFe alloy or NiFeM alloy was obtained by natural drying.

(4) Heat treatment: the self-supporting oxygen evolution anode obtained in step (3) is placed in an oven protected by an inert gas atmosphere, and a self-supporting oxygen evolution anode of NiFe-LDH or NiFeM-LDH is obtained after heat treatment.

Further, in the step (1), the porous nickel-based material may be nickel foam or nickel felt; the water-soluble acid may be one or a mixture of two or more of dilute hydrochloric acid, oxalic acid, and phosphoric acid.

Further, in the step (1), the concentration of the water-soluble acid used for etching is between 5-20 wt.%, and the etching temperature is 80-100°C.

Further, in the step (2), in the metal salt solution, the nickel salt has a mass concentration of 10 to 50 g·L ^-1 ; the iron salt has a mass concentration of 1 to 50 g·L ^{- 1} ; the third component M salt has a mass concentration of 0-10 g·L ^-1 .

Further, in the step (2), the mass concentration of the reducing agent solution is 1-30 g·L ^-1 .

Further, in the step (2), the water-soluble reducing agent is one or a mixture of two or more of borohydride, hydrazine hydrate, ascorbic acid, and ethylene glycol.

Further, in the step (3), the metal salt solution used for printing and the reducing agent solution have a volume ratio of 1:1, and the total amount of coating per unit electrode area is 0.1-1 mL·cm ⁻² .

Further, in the step (3), the heating temperature of the heating stage is between 25°C and 350°C.

Further, in the step (4), the heat treatment temperature is between 200° C. and 500° C., and the annealing time is 2 to 10 hours.

The present invention has the following beneficial effects: (1) the method adopts the preparation process of screen printing, which has the advantages of simple process, easy quality control, good process repeatability, etc., and is suitable for batch preparation of large-area OER electrodes; The oxygen anode has high repeatability and uniformity, and its performance is far superior to commercial IrO ₂ and RuO ₂ electrodes, which can meet the requirements of industrial production. (2) In-situ growth in the screen printing process forms a three-dimensional NiFeM-LDH self-supporting structure, which effectively improves the problems of small specific surface area, poor electron transport performance, low exposure of active sites and slow reaction kinetics of porous nickel-based materials. , enhance the stability and conductivity of the electrode, which is more conducive to the release of oxygen products; no need to use polymer binders that are not conducive to conductivity, and further enhance the conductivity; no noble metal load. (3) This method greatly improves the oxygen evolution catalytic performance through the etching process, the third component doping and heat treatment process, and the obtained oxygen evolution anode has extremely high oxygen evolution activity, stability and repeatability: at 1mol L ^-1 KOH electrolyte solution as an oxygen evolution anode material, when the current density is 10mA cm ^-2 , the oxygen evolution overpotential is 137mV, when the current density is 1A cm ^-2 , the oxygen evolution overpotential is 277mV; 500 In the 1-hour stability test, at a current density of 500mA·cm ^-2 , the performance decay rate is only 0.99mV/h; the relative error of the activity of samples at different positions on the large-area electrode is below 5%.

Description of drawings

Fig. 1 is a schematic flow chart of the screen printing preparation process of the self-supporting oxygen evolution anode of the present invention.

Fig. 2 is a scanning electron microscope picture of the electrode prepared in Example 1 of the present invention.

Fig. 3 is an electrochemical oxygen evolution anode polarization curve of the influence of the third component M on the OER activity of the oxygen evolution anode in Example 2 of the present invention.

Fig. 4 is an electrochemical oxygen evolution anode polarization curve of the influence of acid concentration and etching temperature on the OER activity of the oxygen evolution anode in Example 3 of the present invention.

Fig. 5 is an electrochemical oxygen evolution anode polarization curve of the effect of nickel salt concentration on the OER activity of the oxygen evolution anode in Example 4 of the present invention.

Fig. 6 is an electrochemical oxygen evolution anode polarization curve of the effect of iron salt concentration on the OER activity of the oxygen evolution anode in Example 5 of the present invention.

Fig. 7 is an electrochemical oxygen evolution anode polarization curve of the effect of the concentration of the metal salt of the third component M on the OER activity of the oxygen evolution anode in Example 6 of the present invention.

Fig. 8 is an electrochemical polarization curve of the oxygen evolution anode for the effect of the concentration of the reducing agent on the OER activity of the oxygen evolution anode in Example 7 of the present invention.

Fig. 9 is an electrochemical oxygen evolution anode polarization curve showing the effect of coating amount per unit electrode area on the OER activity of the oxygen evolution anode in Example 8 of the present invention.

Fig. 10 is an electrochemical oxygen evolution anode polarization curve showing the effect of heating temperature on the OER activity of the oxygen evolution anode in Example 9 of the present invention.

Fig. 11 is an electrochemical oxygen evolution anode polarization curve of the effect of heat treatment temperature on the OER activity of the oxygen evolution anode in Example 10 of the present invention.

Fig. 12 is the electrochemical oxygen evolution anode polarization stability curve of the electrode prepared in Example 11 of the present invention.

Fig. 13 is the electrochemical oxygen evolution anodic polarization curve of the uniformity test of the electrode prepared in Example 12 of the present invention.

detailed description

The specific implementation manners of the present invention will be further described below in conjunction with the accompanying drawings and technical solutions.

Embodiment 1: SEM scanning electron microscope test of oxygen evolution anode

Preparation of self-supporting oxygen evolution anode, the preparation process is as follows:

(1) Substrate pretreatment: Use nickel foam with a thickness of 0.3mm as the substrate, cut it into a strip electrode of 6cm×2cm, ultrasonically treat it in acetone for 30min, and then rinse it with absolute ethanol and deionized water for 3 times, and then In 10wt.% dilute hydrochloric acid, etch at 100°C for 10 minutes, and finally dry it at room temperature before use.

(2) Preparation of metal salt solution and reducing agent solution: prepare metal salt solution, wherein the mass concentration of nickel salt is 30g·L ^-1 , the mass concentration of iron salt is 30g·L ^-1 , the mass concentration of the third component metal salt The concentration is 5g·L ^-1 ; prepare sodium borohydride solution with a mass concentration of 20g·L ^-1 .

(3) Self-supporting electrode preparation: the base material was fixed on a heating table, the temperature of the heating table was set at 80° C., and the mesh number of the wire mesh was 400. After the temperature is stabilized, a layer of metal salt solution is applied on the porous nickel substrate by screen printing technology. Then, use the water-soluble reducing agent solution to quickly paint, and after the surface of the substrate is dried, repeat and alternately paint the metal salt solution and the reducing agent solution. After painting, wait for it to dry naturally at room temperature.

(4) Heat treatment after preparation: the substrate with the catalyst grown was transferred to a tube furnace, and heat treated in a nitrogen atmosphere. The initial temperature of the heat treatment was 25°C, the heat treatment temperature was 250°C, and the annealing time was 2h. After the heat treatment, the target oxygen evolution electrode can be obtained.

(5) The results of the scanning electron microscope are shown in Fig. 2, it can be seen that the prepared oxygen evolution electrode is a lamellar self-supporting hydrotalcite structure.

Example 2: The influence of the third component M on the OER activity of the oxygen evolution anode

Preparation of self-supporting oxygen evolution anode, the preparation process is as follows:

(1) Substrate pretreatment: use nickel foam with a thickness of 0.3mm as the substrate, cut it into strips of 6cm×2cm, ultrasonically treat it in acetone for 30min, then rinse it with absolute ethanol and deionized water for 3 times, and then In 20wt.% phosphoric acid, etch at 100°C for 10 minutes, and finally dry at room temperature before use.

(2) Preparation of metal salt solution and reducing agent solution: prepare metal salt solution, wherein the mass concentration of nickel salt is 30g·L ^-1 , the mass concentration of iron salt is 30g·L ^-1 , and the third components are respectively Mo, Mn, Co, to prepare NiFeMo-LDH, NiFeMn-LDH, NiFeCo-LDH oxygen evolution anode, the mass concentration of its metal salt is 5g·L ^-1 ; prepare sodium borohydride solution, its mass concentration is 20g·L ^-1 .

(3) Self-supporting electrode preparation: the base material was fixed on a heating platform, the temperature of the heating platform was set to 100° C., and the mesh number of the wire mesh was 50. After the temperature is stabilized, a layer of metal salt solution is applied on the porous nickel substrate by screen printing technology. Then, use the water-soluble reducing agent solution to quickly paint, and after the surface of the substrate is dried, repeat and alternately paint the metal salt solution and the reducing agent solution. After painting, wait for it to dry naturally at room temperature.

(4) Heat treatment after preparation: the substrate with the catalyst grown was transferred to a tube furnace, and heat treated in a nitrogen atmosphere. The initial temperature of the heat treatment was 25°C, the heat treatment temperature was 300°C, and the annealing time was 2h. After the heat treatment, the target oxygen evolution electrode can be obtained.

(5) Performance test: the target oxygen evolution electrode is placed in an H-type electrolytic cell, the electrolyte is 1MKOH, the reference electrode is a saturated calomel electrode, and the counter electrode is a platinum electrode; the test temperature is 25°C, and the anode is fed with O ₂ 20mL·min ^-1 . Perform a linear scan at a scan rate of 1mV/s, and the test results are shown in Figure 3. It can be seen that the addition of the third component M can improve the OER activity of the oxygen evolution anode.

Example 3: Effects of acid concentration and etching temperature used in etching on OER activity of oxygen evolution anode

Preparation of self-supporting oxygen evolution anode, the preparation process is as follows:

(1) Substrate pretreatment: Use nickel foam with a thickness of 0.3mm as the substrate, cut it into strips of 6cm×2cm, ultrasonically treat it in acetone for 30min, and then rinse it with absolute ethanol and deionized water for 3 times, and then respectively In 5wt.% oxalic acid, etch at 80°C for 10 minutes, in 10wt.% oxalic acid, etch at 90°C for 10 minutes, in 20wt.% oxalic acid, etch at 100°C for 10 minutes, and finally dry at room temperature before use.

(2) Preparation of metal salt solution and reducing agent solution: prepare metal salt solution, wherein the mass concentration of nickel salt is 30g·L ^-1 , the mass concentration of iron salt is 30g·L ^-1 , the mass concentration of the third component metal salt The concentration is 5g·L ^-1 ; prepare sodium borohydride solution with a mass concentration of 20g·L ^-1 .

(3) Self-supporting electrode preparation: the substrate material was fixed on a heating platform, and the temperature of the heating platform was set to 100 ° C. After the temperature was stabilized, a layer of metal salt solution was applied to the porous nickel substrate by screen printing technology. Then, the water-soluble reducing agent solution is used to quickly paint, and after the surface of the substrate is dried, the metal salt solution and the reducing agent solution are alternately scraped repeatedly. After painting, wait for it to dry naturally at room temperature.

(4) Heat treatment after preparation: the substrate with the catalyst grown was transferred to a tube furnace, and heat treated in a nitrogen atmosphere. The initial temperature of the heat treatment was 25°C, the heat treatment temperature was 300°C, and the annealing time was 5h. After the heat treatment, the target oxygen evolution electrode can be obtained.

(5) Performance test: the target oxygen evolution electrode is placed in an H-type electrolytic cell, the electrolyte is 1MKOH, the reference electrode is a saturated calomel electrode, and the counter electrode is a platinum electrode; the test temperature is 25°C, and the anode is fed with O ₂ 20mL·min ^-1 . Perform a linear scan at a scan rate of 1mV/s, and the test results are shown in Figure 4. It can be seen that the increase of acid concentration and etching temperature used in etching can improve the OER activity of oxygen evolution anode.

Example 4: Effect of nickel salt concentration on OER activity of oxygen evolution anode

Preparation of self-supporting oxygen evolution anode, the preparation process is as follows:

(1) Substrate pretreatment: use nickel felt with a thickness of 0.3mm as the substrate, cut into strips of 6cm×2cm, ultrasonically treat in acetone for 30min, then rinse with absolute ethanol and deionized water for 3 times, and then In 10wt.% dilute hydrochloric acid, etch at 100°C for 10 minutes, and finally dry at room temperature before use.

(2) Preparation of metal salt solution and reducing agent solution: prepare metal salt solution, wherein the mass concentration of nickel salt is 10g·L ^-1 , 30g·L ^-1 , 50g·L ^-1 , and the mass concentration of iron salt is 30g·L -1 L ^-1 , the mass concentration of the metal salt of the third component is 5g·L ^-1 ; the sodium borohydride solution is prepared with a mass concentration of 20g·L ^-1 .

(3) Self-supporting electrode preparation: the substrate material was fixed on a heating platform, and the temperature of the heating platform was set to 100 ° C. After the temperature was stabilized, a layer of metal salt solution was applied to the porous nickel substrate by screen printing technology. Then, use the water-soluble reducing agent solution to quickly paint, and after the surface of the substrate is dried, repeat and alternately paint the metal salt solution and the reducing agent solution. After painting, wait for it to dry naturally at room temperature.

(4) Heat treatment after preparation: the substrate with the catalyst grown was transferred to a tube furnace, and heat treated in a nitrogen atmosphere. The initial temperature of the heat treatment was 25°C, the heat treatment temperature was 300°C, and the annealing time was 5h. After the heat treatment, the target oxygen evolution electrode can be obtained.

(5) Performance test: the target oxygen evolution electrode is placed in an H-type electrolytic cell, the electrolyte is 1MKOH, the reference electrode is a saturated calomel electrode, and the counter electrode is a platinum electrode; the test temperature is 25°C, and the anode is fed with O ₂ 20mL·min ^-1 . A linear scan was performed at a scan rate of 1 mV/s, and the test results are shown in Figure 5. It can be seen that the increase of the nickel salt concentration can improve the OER activity of the oxygen evolution anode.

Example 5: Effect of Iron Salt Concentration on OER Activity of Oxygen Evolution Anode

Preparation of self-supporting oxygen evolution anode, the preparation process is as follows:

(1) Substrate pretreatment: use nickel foam with a thickness of 0.3mm–1.5mm as the substrate, cut it into strips of 6cm×2cm, ultrasonically treat it in acetone for 30min, and then rinse it with absolute ethanol and deionized water for 3 times , and then etched in 10wt.% dilute hydrochloric acid at 100°C for 10 minutes, and finally dried at room temperature before use.

(2) Preparation of metal salt solution and reducing agent solution: prepare metal salt solution, wherein the mass concentration of nickel salt is 30g·L ^-1 , and the mass concentration of iron salt is 1g·L ^-1 , 25g·L ^-1 , 50g· L ^-1 , the mass concentration of the metal salt of the third component is 5g·L ^-1 ; the sodium borohydride solution is prepared with a mass concentration of 20g·L ^-1 .

(3) Self-supporting electrode preparation: the substrate material was fixed on a heating platform, and the temperature of the heating platform was set at 80°C. After the temperature was stabilized, a layer of metal salt solution was applied to the porous nickel substrate by screen printing technology. Then, use the water-soluble reducing agent solution to quickly paint, and after the surface of the substrate is dried, repeat and alternately paint the metal salt solution and the reducing agent solution. After painting, let it dry naturally at room temperature to obtain the target oxygen evolution catalyst electrode.

(4) Heat treatment after preparation: the substrate with the catalyst grown was transferred to a tube furnace, and heat treated in a nitrogen atmosphere. The initial temperature of the heat treatment was 25°C, the heat treatment temperature was 300°C, and the annealing time was 5h. After the heat treatment, the target oxygen evolution electrode can be obtained.

(5) Performance test: the target oxygen evolution electrode is placed in an H-type electrolytic cell, the electrolyte is 1MKOH, the reference electrode is a saturated calomel electrode, and the counter electrode is a platinum electrode; the test temperature is 25°C, and the anode is fed with O ₂ 20mL·min ^-1 . Perform a linear scan at a scan rate of 1mV/s, and the test results are shown in Figure 6. It can be seen that with the increase of the iron salt concentration, the OER activity of the oxygen evolution anode first increases and then decreases, and the OER activity is the highest when the iron salt concentration is 25 g·L ^-1 .

Example 6: Effect of the third component M metal salt concentration on the OER activity of the oxygen evolution anode

Preparation of self-supporting oxygen evolution anode, the preparation process is as follows:

(1) Substrate pretreatment: use nickel felt with a thickness of 0.4mm as the substrate, cut into strips of 6cm×2cm, ultrasonically treat in acetone for 30min, then rinse with absolute ethanol and deionized water for 3 times, and then In 20wt.% phosphoric acid, etch at 100°C for 10 minutes, and finally dry at room temperature before use.

(2) Preparation of metal salt solution and reducing agent solution: prepare metal salt solution, wherein the mass concentration of nickel salt is 30g·L ^-1 , the mass concentration of iron salt is 30g·L ^-1 , the mass concentration of the third component metal salt Concentrations are 0, 5g·L ^-1 , 10g·L ^-1 ; prepare sodium borohydride solution with a mass concentration of 20g·L ^-1 .

(3) Self-supporting electrode preparation: the substrate material was fixed on a heating platform, and the temperature of the heating platform was set to 100 ° C. After the temperature was stabilized, a layer of metal salt solution was applied to the porous nickel substrate by screen printing technology. Then, use the water-soluble reducing agent solution to quickly paint, and after the surface of the substrate is dried, repeat and alternately paint the metal salt solution and the reducing agent solution. After painting, wait for it to dry naturally at room temperature.

(4) Heat treatment after preparation: the substrate with the catalyst grown was transferred to a tube furnace, and heat treated in a nitrogen atmosphere. The initial temperature of heat treatment was 25°C, the heat treatment temperature was 250°C, and the annealing time was 5h. After the heat treatment, the target oxygen evolution electrode can be obtained.

(5) Performance test: the target oxygen evolution electrode is placed in an H-type electrolytic cell, the electrolyte is 1MKOH, the reference electrode is a saturated calomel electrode, and the counter electrode is a platinum electrode; the test temperature is 25°C, and the anode is fed with O ₂ 20mL·min ^-1 . Perform a linear sweep at a scan rate of 1mV/s, and the test results are shown in Figure 7. It can be seen that the increase of the concentration of the third component M metal salt can improve the OER activity of the oxygen evolution anode.

Example 7: Effect of reducing agent concentration on OER activity of oxygen evolution anode

Preparation of self-supporting oxygen evolution anode, the preparation process is as follows:

(1) Substrate pretreatment: use nickel foam with a thickness of 0.3mm as the substrate, cut it into strips of 6cm×2cm, ultrasonically treat it in acetone for 30min, then rinse it with absolute ethanol and deionized water for 3 times, and then In 20wt.% oxalic acid, etch at 100°C for 10 minutes, and finally dry at room temperature before use.

(2) Preparation of metal salt solution and reducing agent solution: prepare metal salt solution, wherein the mass concentration of nickel salt is 30g·L ^-1 , the mass concentration of iron salt is 30g·L ^-1 , the mass concentration of the third component metal salt The concentration is 5g·L ^-1 ; prepare sodium borohydride solution with mass concentration of 1g·L ^-1 , 10g·L ^-1 , 30g·L ^-1 .

(3) Self-supporting electrode preparation: the substrate material was fixed on a heating platform, and the temperature of the heating platform was set at 80°C. After the temperature was stabilized, a layer of metal salt solution was applied to the porous nickel substrate by screen printing technology. Then, use the water-soluble reducing agent solution to quickly paint, and after the surface of the substrate is dried, repeat and alternately paint the metal salt solution and the reducing agent solution. After painting, let it dry naturally at room temperature to obtain the target oxygen evolution catalyst electrode.

(4) Heat treatment after preparation: the substrate with the catalyst grown was transferred to a tube furnace, and heat treated in a nitrogen atmosphere. The initial temperature of the heat treatment was 25°C, the heat treatment temperature was 250°C, and the annealing time was 10h. After the heat treatment, the target oxygen evolution electrode can be obtained.

(5) Performance test: the target oxygen evolution electrode is placed in an H-type electrolytic cell, the electrolyte is 1MKOH, the reference electrode is a saturated calomel electrode, and the counter electrode is a platinum electrode; the test temperature is 25°C, and the anode is fed with O ₂ 20mL·min ^-1 . Perform a linear scan at a scan rate of 1mV/s, and the test results are shown in Figure 8. It can be seen that the increase of reducing agent concentration can improve the OER activity of oxygen evolution anode.

Example 8: Influence of coating amount per unit electrode area on OER activity of oxygen evolution anode

Preparation of self-supporting oxygen evolution anode, the preparation process is as follows:

(1) Substrate pretreatment: use nickel foam with a thickness of 0.3mm as the substrate, cut it into strips of 6cm×2cm, ultrasonically treat it in acetone for 30min, then rinse it with absolute ethanol and deionized water for 3 times, and then In 10wt.% dilute hydrochloric acid, etch at 100°C for 60min, and finally dry at room temperature before use.

(2) Preparation of metal salt solution and reducing agent solution: prepare metal salt solution, wherein the mass concentration of nickel salt is 30g·L ^-1 , the mass concentration of iron salt is 30g·L ^-1 , the mass concentration of the third component metal salt The concentration is 5g·L ^-1 ; prepare an ascorbic acid solution with a mass concentration of 5g·L ^-1 .

(3) Self-supporting electrode preparation: the substrate material was fixed on a heating platform, and the temperature of the heating platform was set at 80°C. After the temperature was stabilized, a layer of metal salt solution was applied to the porous nickel substrate by screen printing technology. Then, use the water-soluble reducing agent solution to quickly paint, and after the surface of the substrate is dried, repeat and alternately paint the metal salt solution and the reducing agent solution. After painting, let it dry naturally at room temperature to obtain the target oxygen evolution catalyst electrode. The amount of the solution was controlled so that the coating amount per unit electrode area was 0.1 mL·cm ^-2 , 0.5 mL·cm ^-2 , and 1 mL·cm ^-2 .

(4) Heat treatment after preparation: the substrate with the catalyst grown was transferred to a tube furnace, and heat treated in a nitrogen atmosphere. The initial temperature of the heat treatment was 25°C, the heat treatment temperature was 250°C, and the annealing time was 10h. After the heat treatment, the target oxygen evolution electrode can be obtained.

(5) Performance test: the target oxygen evolution electrode is placed in an H-type electrolytic cell, the electrolyte is 1MKOH, the reference electrode is a saturated calomel electrode, and the counter electrode is a platinum electrode; the test temperature is 25°C, and the anode is fed with O ₂ 20mL·min ^-1 . Perform a linear sweep at a scan rate of 1mV/s, and the test results are shown in Figure 9. It can be seen that the increase of the coating amount per unit click area can improve the OER activity of the oxygen evolution anode.

Example 9: Effect of Heating Temperature on OER Activity of Oxygen Evolution Anode

Preparation of self-supporting oxygen evolution anode, the preparation process is as follows:

(1) Substrate pretreatment: use nickel foam with a thickness of 0.3mm as the substrate, cut it into strips of 6cm×2cm, ultrasonically treat it in acetone for 30min, then rinse it with absolute ethanol and deionized water for 3 times, and then In 10wt.% phosphoric acid, etch at 100°C for 60 minutes, and finally dry at room temperature before use.

(2) Preparation of metal salt solution and reducing agent solution: prepare metal salt solution, wherein the mass concentration of nickel salt is 30g·L ^-1 , the mass concentration of iron salt is 30g·L ^-1 , the mass concentration of the third component metal salt The concentration is 5g·L ^-1 ; prepare a hydrazine hydrate solution with a mass concentration of 1g·L ^-1 .

(3) Self-supporting electrode preparation: place the substrate material on a heating table and fix it, and set the temperature of the heating table to 25°C, 100°C, and 350°C. After the temperature is stable, paint a layer of metal on the porous nickel substrate by screen printing technology. saline solution. Then, use the water-soluble reducing agent solution to quickly paint, and after the surface of the substrate is dried, repeat and alternately paint the metal salt solution and the reducing agent solution. After painting, wait for it to dry naturally at room temperature.

(4) Heat treatment after preparation: the substrate with the catalyst grown was transferred to a tube furnace, and heat treated in a nitrogen atmosphere. The initial temperature of the heat treatment was 25°C, the heat treatment temperature was 350°C, and the annealing time was 2h. After the heat treatment, the target oxygen evolution electrode can be obtained.

(5) Performance test: the target oxygen evolution electrode is placed in an H-type electrolytic cell, the electrolyte is 1MKOH, the reference electrode is a saturated calomel electrode, and the counter electrode is a platinum electrode; the test temperature is 25°C, and the anode is fed with O ₂ 20mL·min ^-1 . Carry out a linear scan at a scan rate of 1mV/s, and the test results are shown in Figure 10. It can be seen that the increase of heating temperature can improve the OER activity of oxygen evolution anode.

Example 10: Effect of heat treatment temperature on OER activity of oxygen evolution anode

Preparation of self-supporting oxygen evolution anode, the preparation process is as follows:

(1) Substrate pretreatment: use nickel foam with a thickness of 0.3mm as the substrate, cut it into strips of 6cm×2cm, ultrasonically treat it in acetone for 30min, then rinse it with absolute ethanol and deionized water for 3 times, and then In 10wt.% dilute hydrochloric acid, etch at 100°C for 10 minutes, and finally dry at room temperature before use.

(2) Preparation of metal salt solution and reducing agent solution: prepare metal salt solution, wherein the mass concentration of nickel salt is 30g·L ^-1 , the mass concentration of iron salt is 30g·L ^-1 , the mass concentration of the third component metal salt The concentration is 5g·L ^-1 ; prepare sodium borohydride solution with a mass concentration of 20g·L ^-1 .

(3) Self-supporting electrode preparation: the substrate material was fixed on a heating platform, and the temperature of the heating platform was set to 100 ° C. After the temperature was stabilized, a layer of metal salt solution was applied to the porous nickel substrate by screen printing technology. Then, use the water-soluble reducing agent solution to quickly paint, and after the surface of the substrate is dried, repeat and alternately paint the metal salt solution and the reducing agent solution. After painting, wait for it to dry naturally at room temperature.

(4) Heat treatment after preparation: transfer the substrate with catalyst growth to a tube furnace, and heat treat in a nitrogen atmosphere. 2h. After the heat treatment, the target oxygen evolution electrode can be obtained.

(5) Performance test: the target oxygen evolution electrode is placed in an H-type electrolytic cell, the electrolyte is 1MKOH, the reference electrode is a saturated calomel electrode, and the counter electrode is a platinum electrode; the test temperature is 25°C, and the anode is fed with O ₂ 20mL·min ^-1 . Perform a linear sweep at a scan rate of 1mV/s, and the test results are shown in Figure 11. It can be seen that the increase of heat treatment temperature can improve the OER activity of oxygen evolution anode.

Example 11: OER Stability Test of Oxygen Evolution Anode

(1) Substrate pretreatment: use nickel felt with a thickness of 0.3mm as the substrate, cut it into a sheet of 6cm×8cm, ultrasonically treat it in acetone for 30min, then rinse it with absolute ethanol and deionized water for 3 times, and then In 10wt.% phosphoric acid, etch at 100°C for 10 minutes, and finally dry at room temperature before use.

(2) Preparation of metal salt solution and reducing agent solution: prepare metal salt solution, wherein the mass concentration of nickel salt is 30g·L ^-1 , the mass concentration of iron salt is 30g·L ^-1 , the mass concentration of the third component metal salt The concentration is 5g·L ^-1 ; prepare ethylene glycol solution with a mass concentration of 20g·L ^-1 .

(3) Self-supporting electrode preparation: the substrate material was fixed on a heating platform, and the temperature of the heating platform was set to 100 ° C. After the temperature was stabilized, a layer of metal salt solution was applied to the porous nickel substrate by screen printing technology. Then, use the water-soluble reducing agent solution to quickly paint, and after the surface of the substrate is dried, repeat and alternately paint the metal salt solution and the reducing agent solution. After painting, wait for it to dry naturally at room temperature.

(4) Heat treatment after preparation: the substrate with the catalyst grown was transferred to a tube furnace, and heat treated in a nitrogen atmosphere. The initial temperature of the heat treatment was 25°C, the heat treatment temperature was 500°C, and the annealing time was 2h. After the heat treatment, the target oxygen evolution electrode can be obtained.

(5) Stability test: the target oxygen evolution electrode is placed in an H-type electrolytic cell, the electrolyte is 1M KOH, the reference electrode is a saturated calomel electrode, and the counter electrode is a platinum electrode; the test temperature is 25°C, and the anode is connected to O ₂ 20mL·min ^-1 . The stability of the electrode was tested for 500h under the condition of a constant current of 500mA.cm ^-2 , and the test results are shown in Fig. 12 . It can be seen that the oxygen evolution anode prepared by silk printing has good stability. In the 500-hour stability test, the performance decay rate is only 0.99mV/h at a current density of 500mA·cm ^-2 .

Example 12: OER uniformity test of oxygen evolution anode

Preparation of self-supporting oxygen evolution anode, the preparation process is as follows:

(1) Substrate pretreatment: use nickel felt with a thickness of 0.3mm as the substrate, cut it into a sheet of 6cm×8cm, ultrasonically treat it in acetone for 30min, then rinse it with absolute ethanol and deionized water for 3 times, and then In 20wt.% oxalic acid, etch at 100°C for 10 minutes, and finally dry at room temperature before use.

(2) Preparation of metal salt solution and reducing agent solution: prepare metal salt solution, wherein the mass concentration of nickel salt is 30g·L ^-1 , the mass concentration of iron salt is 30g·L ^-1 , the mass concentration of the third component metal salt The concentration is 5g·L ^-1 ; prepare sodium borohydride solution with a mass concentration of 20g·L ^-1 .

(3) Self-supporting electrode preparation: the substrate material was fixed on a heating platform, and the temperature of the heating platform was set to 100 ° C. After the temperature was stabilized, a layer of metal salt solution was applied to the porous nickel substrate by screen printing technology. Then, use the water-soluble reducing agent solution to quickly paint, and after the surface of the substrate is dried, repeat and alternately paint the metal salt solution and the reducing agent solution. After painting, wait for it to dry naturally at room temperature.

(4) Heat treatment after preparation: the substrate with the catalyst grown was transferred to a tube furnace, and heat treated in a nitrogen atmosphere. The initial temperature of the heat treatment was 25°C, the heat treatment temperature was 350°C, and the annealing time was 2h. After the heat treatment, the target oxygen evolution electrode can be obtained.

(5) Performance test: Cut the target oxygen evolution electrode evenly into 8 strips of 1cm×6cm, and place them in the H-type electrolytic cell respectively. The electrolyte is 1MKOH, the reference electrode is a saturated calomel electrode, and the counter electrode is platinum. Electrode; the test temperature is 25°C, and the anode is fed with O ₂ 20 mL·min ^-1 . Perform a linear sweep at a scan rate of 1mV/s, and the test results are shown in Figure 13. It can be seen that the large-area oxygen evolution anode prepared by silk printing has good uniformity, and the relative error of sample activity at different positions is below 5%.

Claims (9)

1. A silk-screen printing preparation method of a self-supporting oxygen evolution anode is characterized by comprising the following steps:

(1) Substrate pretreatment: taking a porous nickel-based material as an electrode substrate, respectively cleaning the electrode substrate in acetone, absolute ethyl alcohol and deionized water, then etching the electrode substrate in water-soluble acid, and finally drying the electrode substrate at room temperature for later use;

(2) Preparing a metal salt solution and a reducing agent solution: dissolving nickel salt and iron salt in deionized water to prepare a metal salt solution or dissolving nickel salt, iron salt and a third component M salt in deionized water to prepare a metal salt solution; dissolving a water-soluble reducing agent in deionized water to prepare a reducing agent solution; the third component M is one or a mixture of more than two of Mo, mn, co, W, P and B;

(3) A temperature-controllable vacuum adsorption heating platform is additionally arranged on a printing plane of the screen printing machine; fixing the porous nickel-based material on a heating table, and brushing a layer of the metal salt solution prepared in the step (2) on the porous nickel-based material by adopting a silk screen with the mesh number of 50-400 through a silk screen printing technology; then, adopting the reducing agent solution prepared in the step (2) as silk-screen slurry, and repeatedly and alternately silk-screening the metal salt solution and the reducing agent solution; after finishing silk-screen printing, naturally drying at room temperature to obtain a self-supporting oxygen evolution anode of NiFe alloy or NiFeM alloy;

(4) And (3) heat treatment: and (4) placing the self-supporting oxygen evolution anode obtained in the step (3) in an oven protected by inert gas atmosphere, and performing heat treatment to obtain the self-supporting oxygen evolution anode of NiFe-LDH or NiFeM-LDH.

2. The method for preparing a self-supporting oxygen evolution anode by screen printing according to claim 1, wherein in the step (1), the porous nickel-based material is foamed nickel or nickel felt; the water-soluble acid is one or more of diluted hydrochloric acid, oxalic acid and phosphoric acid.

3. The method for preparing a self-supporting oxygen evolution anode by screen printing according to claim 1 or 2, wherein in the step (1), the concentration of the water-soluble acid used for etching is between 5 and 20wt.%, and the etching temperature is between 80 and 100 ℃.

4. The process for preparing self-supporting oxygen evolution anode by screen printing as claimed in claim 1 or 2, wherein in the step (2), the mass concentration of the nickel salt in the metal salt solution is 10-50 g-L ^-1 (ii) a The mass concentration of the ferric salt is 1-50 g.L ^-1 (ii) a The mass concentration of the third component M salt is 0-10 g.L ^-1 。

5. The process according to claim 1 or 2, characterized in that in step (2), the mass concentration of the reducing agent solution is 1-30 g.L ^-1 。

6. The method according to claim 1 or 2, wherein in the step (2), the water-soluble reducing agent is one or a mixture of two or more of borohydride, hydrazine hydrate, ascorbic acid and ethylene glycol.

7. The process for preparing self-supporting oxygen evolving anode by screen printing according to claim 1 or 2, wherein in the step (3), the metal salt solution and the reducing agent solution are used for printing in a volume ratio of 1:1, the total coating amount per unit electrode area is 0.1-1 mL cm ^-2 。

8. The process for the screen-printing preparation of a self-supporting oxygen evolving anode according to claim 1 or 2 characterized in that in step (3) the heating stage is heated to a temperature between 25 ℃ and 350 ℃.

9. The screen printing preparation method of the self-supporting oxygen evolution anode according to the claim 1 or 2, characterized in that, in the step (4), the heat treatment temperature is between 200 ℃ and 500 ℃ and the annealing time is 2-10 h.

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